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Abstract The modern era of refractive surgery began with the introduction of excimer laser photoablatoin by Trokel in 1983, PRK was first performed in 1987 and LASIK was introduced in 1989. Due its submicron precision and the lack of thermal damage to the surrounding tissues, LASIK rapidly replaced most of the other refractive procedures, such as radial keratotomy (RK), Astigmatic keratotomy (AK) and automated lamellar keratotomy (ALK). Most of the refractive procedures are associated with a residual refractive error. LASIK can be used for treatment of these errors taking in consideration a few points: LASIK is preferable for higher myopia as it avoids corneal haze and regression, and loss of spectacle corrected visual acuity that can occur after larger PRK corrections. LASIK enhancement can be done either by elevating the flap or cutting a new flap. Care should be taken to leave an adequate stromal bed. A total corneal thickness of no less than 400 µm is mandatory to avoid ectasia. Lifting the flap was relatively easy to perform and did not results in visual morbidity in eyes treated from 3 up to 18 months after primary LASIK. LASIK after PRK is associated with a less haze and regression thanif PRK was to be use for enhancement. No the uses of LASIK to correct hypermetropic shift following PTK is almost without any difficulties or hazars. LASIK after Laser thermo keratoplasty (LTK). The predictability and efficacy seems to be inferior than that with hyperopic corneas treated with LASIK alone but equally safe. LASIK after RK is promising and safe procedure and is associated with less complications than with PRK following RK. While performing LASIK after RK, care should be taken to avoud reopening of on the radial incisions. LASIK after AK is highly effective and predictable with no major compilations. However, LASIK is not highly predictable in treatment of residual refractive errors after ALK. LASIK can be safely performed after CK. Conductive keratoplasty appears to have little effect on flap creation, refractive and topographic effects of the flap and on the ability to relift the flap manually weeks after it is initially cut. Before performing LASIK for correction of a refractive error following any pervious ocular surgery such as pterygium removal, it must be made sure that refraction has stabilized and corneal thickness is adequate for such procedure. |